To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
The rapid development of the information industry, particularly the increasing demand from the mobile Internet and the Internet of Things (IoT), brings about unprecedented challenges in the future mobile communications technology. According to the ITU-R M. [IMT.BEYOND 2020.TRAFFIC] issued by the International Telecommunication Union (ITU), it can be expected that, by 2020, mobile services traffic will grow nearly 1,000 times as compared with that in 2010 (4G era), and the number of user device connections will also be over 17 billion, and with a vast number of IoT devices gradually expand into the mobile communication network, the number of connected devices will be even more astonishing. In response to this unprecedented challenge, the communications industry and academia have prepared for the 2020s by launching an extensive study of the fifth generation of mobile communications technology (5G). Currently, in ITU-R M. [IMT.VISION] from ITU, the framework and overall objectives of the future 5G have been discussed, where the demands outlook, application scenarios and various important performance indexes of 5G have been described in detail. In terms of new demands in 5G, the ITU-R M. [IMT.FUTURE TECHNOLOGY TRENDS] from ITU provides information related to the 5G technology trends, which is intended to address prominent issues such as significant improvement on system throughput, consistency of the user experience, scalability so as to support IoT, delay, energy efficiency, cost, network flexibility, support for new services and flexible spectrum utilization, etc.
For more diverse business scenarios of 5G, the flexible multiple access technology is required to support various scenarios and business requirements. For example, for a business scenario with massive connections, how to allow more user equipments (UEs) to access in limited resources becomes a core problem to be solved in the 5G multiple access technology. In the present 4G LTE network, the orthogonal frequency division multiplexing (OFDM) based multiple access technologies are mainly employed, for example, downlink OFDM Access (OFDMA) and uplink single-carrier frequency division multiple access (SC-FDMA). However, obviously, the existing orthogonal multiple access technologies cannot meet the requirements of 5G in improving the spectrum efficiency by 5 to 15 times and having millions of UEs accessed per square kilometer. The non-orthogonal multiple access (NMA) technology can greatly increase the connection number of supported UEs since it shares the same resources to multiple UEs. Since there are more opportunities for UEs to access, the overall throughput of network and the spectrum efficiency are improved. In addition, for the massive machine type communication (mMTC) scenario, considering the cost of the terminal and the complexity in implementation, it may need to use more simply operated multiple access technologies. For business scenarios requiring low delay or low power consumption, the use of the non-orthogonal multiple access technology can better achieve scheduling-free and contention-based access and further low-delay communication, and can shorten the startup time and reduce the power consumption of the equipment.
The currently major non-orthogonal multiple access technologies in research are, multiple user shared access (MUSA), non-orthogonal multiple access (NOMA), pattern division multiple access (PDMA), sparse code multiple access (SCMA) and interleave division multiple access (IDMA) etc. For MUSA, UEs are distinguished by code words, for SCMA, UEs are distinguished by a codebook, for NOMA, UEs are distinguished by power, for PDMA, UEs are distinguished by different feature patterns, and for IDMA, different UEs are distinguished by interleaver. For details of IDMA, please refer to Li Ping, Lihai Liu, Keying Wu and W. K. Leung, “Interleave Division Multiple Access”, IEEE Transactions on Wireless Communication, Vol. 5, No. 4, pp. 938-947, April 2006.
Accordingly, it is necessary to provide an effective multiple access implementation scheme, to better achieve scheduling-free contention-based access, low-delay communication, short startup time, low power consumption of the equipment and more, thus to ultimately support more diverse business scenarios and business requirements of 5G.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.